Robert Downey Jr. massaged Chris Evans' Civil War injury

Robert Downey Jr. saved the day when his 'Captain America: Civil War' co-star Chris Evans injured his arm on set.

The 51-year-old actor - who has played Iron Man in the Marvel Cinematic Universe since 2008 - became a real-life superhero when he was shown scenes of Evans [Captain America] pretending to hold up a helicopter and strained the muscles in his huge from flexing.

Downey told People magazine: "I came to set to start shooting and they show me a couple minutes [of footage]. Like, 'Here's what we've been doing.' This is a shot where Cap is holding this big [helicopter] and I say, 'You know what? All the things he's done, that's the one that was going to injure him.' I knew it.

"Because they're saying, 'Flex and hold it!' It wasn't the other 3,000 stunts, it was that."

Asked about shooting the scene, which features in the trailer for the movie, Evans, 34, admitted: "My arm did get all messed up."

Caring Downey placed what he calls "massaging guns" all over his pal's arm to soother his pain.

Evans recalled: "I went to (Downey's) trailer and he put these things all over my arm. I did actually mess my arm up doing that helicopter thing."

During the joint interview the hunky actor joked that he was still in pain.

He told Downey: "[The arm] is still a mess, actually ... I need your thing more."

And he replied:" I've got it ready for you."

Downey and Evans are joined by Tom Holland, Elizabeth Olsen, Paul Bettany, Paul Rudd and Jeremy Renner in the action movie.